The classification for a variety of the methods for coating painting depends on whether or not a solvent is used, and can be generally divided into powder coating and liquid coating. In short, if a solvent is used, the coating process can be classified as a liquid coating; if solvent is unnecessary, it can be classified as powder coating.
Since solvents used in the process of coating can cause air and water pollution to the environment, the cost involved for environmental protection is increasing as the standards required for environmental protection are getting stricter. In addition, in considering the quality of the coating, powder coating has some advantages over liquid coating described as follows: pin holes are rarely found in powder coating; a thicker coating can be attained in one process, unlike a liquid coating, in which running of the paint usually occurs if the coat applied is too thick. Moreover, in the process of liquid coating, a primer coat and at least one finish coat is necessary, in contrast, powder coating can be completed by an application of a single coat, in other words, the process of powder coating is comparably simple. In addition, the process can proceed faster, and accordingly, the cost is lowered.
For the forgoing reasons, the application of powder coatings has been becoming more widely utilized, so the importance of improving the process of powder coating increases. Among the improved measures, some relate to the quality, some, on the other hand, relate to bringing down the cost. Regarding the cost, the recycling rate of a coating material is considered an important factor. Among the coating processes applied, aside from collecting the un-adhered coating material, there is no solution yet to solve the problem of the waste of coating material in the coating process.
The layout of an conventional powder coating process is shown in FIG. 1. On the left hand side of the figure, an operator attaches an object C to be coated to the jig 1. The object C and the jig 1 carried by the conveyer 2 would follow the direction indicated by the arrow and enter the coating chamber 200'. There is a coating material recycler 100' in the coating chamber 200', which can recycle the powered coating material which does not adhere to the object C in the coating process After the coating process is finished, the object C and the jig 1 enter the baking chamber 300' where the baking process proceeds. After the baking process is completed, the aerator (shown in the right hand side of FIG. 1) pulls off the object C from jig 1 leaving jig 1 on the conveyer 2, the entire cycle of coating process is thus complete, and then another cycle will begin following the same procedures as described above.
In the coating process, objects C are hung up and are carried along a specific route. The jigs used in the coating process would also be covered with significant amount of coating material. As the number of jigs used in a production line is enormous, the amount of coating material accumulated on the jigs would be to great to be ignored. However, since the same jig is used in coating and baking process, the coating material covered on the jig cannot be recycled after being baked. Moreover, if the jig is continually used, the coating material accumulated on the jig would grow thicker until the layer is too thick to be mounted with the object to be coated. Generally, a jig cannot be used over twenty times and then has to be discarded, and that increases the cost of the process. The object of the present invention is to improve the rate of the recycled coating material and to increase the life span of the jig.